Approximately how many cups of chopped rhubarb do I need for this recipe? Mine is already cut up and I don't have a scale!
Looking at the recipe, I'd cook more than enough rhubarb (6-8 cups?) with sugar to taste and follow the steps to the puree method. There's a picture of the blender on the recipe slideshow, so at this point you can eyeball how much rhubarb to use (looks about 2 cups after pureeing?).
The risk is using too much rhubarb and not having enough yolks to set the curd, so err on the side of less rhubarb - that said there should be a reasonable margin of error here.
Recipe calls for 3/4 pounds rhubard and 1 cup holds about 4 ounces rhubard uncooked and cut up. So I would use about 3 cups. Sounds like Sarah knows a lot more about cooking rhubard than I do, so I would heed her good advice about erring on the side of less instead of more.